Novel TiO 2 -ZnO Nanocomposite-Based Highly Sensitive Optical Fiber Humidity Sensor with Fast Response/Recovery Time

This research aims to develop an optical fiber relative humidity (RH) sensor with high sensitivity, a linear response over a wide dynamic range, and optimized response/recovery times using a simple sensing configuration. The proposed sensor employs intensity modulation through evanescent wave (EW) absorption, achieved by coating a short, centrally decladded region of a plastic-clad silica (PCS) fiber with a TiO₂-ZnO nanocomposite-doped silica sol-gel thin film. Extensive experimental studies were conducted to assess the sensor's performance. The developed sensor demonstrates enhanced sensitivity of 0.0078 RH⁻¹, linear response across a wide dynamic range of 20%–85%RH and significantly fast response/recovery times of 0.03/0.04s/%RH with a resolution of ±0.47% RH. It also exhibits excellent reversibility, repeatability and reliability, making it suitable for real-field applications.